河北平泉下营坊不对称褶曲的厘定及控岩控矿意义

着重介绍了河北平泉下营坊一带主干构造格架──ＮＥ向Ｓ状不对称褶曲的几何特征、形成机制、变形环境及控岩控矿作用。区域应力场分析及岩组分析揭示了该区在ＮＥ向左行斜冲剪切机制下，夹持在块状太古代变质基底及侏罗系火山岩间的元古界层状岩层，因上、下界面的滑脱剪切所造成的变形效应以及所处的中温、低压变形环境。不对称褶曲翼部地层的顺层滑脱和转折端部位的虚脱为本区中酸性岩浆活动提供了侵位通道和空间。向ＳＷＷ倾伏的不对称褶曲的背斜转折端与ＥＷ向及ＮＮＥ向断裂的复合构造是控制下营坊南梁斑岩体及斑岩型铜矿的构造。

IDENTIFICATION OF S-TYPE ASYMMETRICAL FOLD AND ITS ACTION ON CONTROLLING MAGMATISM AND MINERALIZATION IN XIAYINGFANG DISTRICT,PINGQUAN,HEBEI PROVINCE

Xiayingfang district, Pingquan, Hebei Province, is called Yongan - Xiaylngfang-Maojiagou metallogenetic belt, in which the bedded sedimentary rocks, sandstones and limestones of Proterozoic Changcheng System and overlying Jurassic volcanoclastic rocks and underlying Archean metamorphic crystal basement with unconformities exist. Xiayingfang district is located in the east segment of Yanshan platformal fold belts, North China platform. And Yanshan conjunct arc passes west to the area. The exist evidence of a S-type asymmetrical fold with NE trending is described and its genetic mechanism and deformation environment are discussed in this paper, which show that the fold resulted from the sinistral shear with oblique thrust on the two unconformities as decollements. Bedding decoupling in the long limbs controls igneous veins in NE trending and the decoupling in the hinge zone of fold controls intrusion that intruded from SWW to NEE along the hinges.The conjuncted place of plunging crown of fold and EW trending and NNE trending faults,therefore, is a promising prospect. The analyses of regional stress field and quartz C-axis of rocks from the asymmetrical fold reveal that the deformation was in the environment of middle temperature and low pressure.